1. Field of the Invention
The present invention relates to a sheet processing apparatus connected to an image forming apparatus for collecting, aligning and post-processing the sheets discharged from the image forming apparatus, and more particularly to an apparatus having a stacking tray for stacking and aligning a plurality of sheets temporarily.
2. Description of the Related Art
Hitherto, the sheet processing apparatus is connected to an image forming apparatus, for conveying the sheets discharged from the image forming apparatus, aligning and sewing, and moving the sewn sheet bundle to a stacking tray. At this time, while processing the sheet bundle, next sheet bundle cannot be sent into the stacking tray, and the throughput is lowered. To solve the problem of throughput decline, it has been attempted to produce a post-processing time by temporarily superimposing and stacking two sheets before the nip section of the roller for discharging the sheets to the sheet stacking tray, before discharging sheets to the sheet stacking tray, and discharging two sheets in superimposed state onto the stacking tray, thereby preventing decline of throughput.
However, as shown in Japanese Patent Application Laid-Open (JP-A) No. 9-235069, in the configuration designed to discharge sheets to a stacking tray, after superimposing while aligning the ends of two sheets by hitting the sheets conveyed from above to below against the roller for discharging sheets to the stacking tray, since the end of sheet abuts against the discharge roller as sheet end stopper by the own weight, a wide space is needed for temporarily stacking the sheet in the conveyance path up to the discharge roller (a longer conveyance path than the maximum sheet size for post-processing is needed), and the apparatus is larger in size, and is higher in cost.
Or as disclosed in JP-A No. 1-127556, by stopping a first sheet conveyance roller, a first sheet is stopped before stacking tray discharge roller, and when the end of second sheet reaches before discharge roller pair by second sheet conveyance roller, by driving the first sheet conveyance roller, two sheets are conveyed simultaneously, and two sheets in superimposed state are discharged onto stacking tray, and even in such configuration, enough space for completely holding the first sheet within the conveyance path is required, and the apparatus is larger in size and higher in cost.
In the configurations disclosed in JP-A No. 9-235069 and in JP-A No. 1-127556, by stopping second sheet once when superimposing two sheets, the paper space to third sheet (the time until third sheet is stacked on stacking tray) is shortened, and enough aligning process time may not be produced.
It is hence an object of the invention to provide an inexpensive sheet processing apparatus of small size, not lowered in throughput of the connected image processing apparatus.
To solve the problems, a representative configuration of sheet processing apparatus of the invention is a sheet processing apparatus for processing sheets including a stacking tray for stacking sheets for post-processing, a discharge roller pair aparting from each other for discharging sheets on the stacking tray, a first path for conveying sheets to the discharge roller pair, shorter than the length of the minimum sheet size being conveyed in the sheet conveying direction, a second path branched from the first path and meeting with the first path at the upstream side of the discharge roller pair in the sheet conveying direction, a path switching member disposed at the branching point for guiding the sheets selectively to the first path or second path, a first conveyance roller disposed at the upstream side in the sheet conveying direction from the branching point, and a controlling device for controlling sheet conveyance, in which the controlling device controls to change over the path switching member, guide the conveyed first sheet into the first path, apart the discharge roller pair from each other after the front end of the first sheet has passed the discharge roller pair, change over the path switching member after the rear end of the first sheet has passed the discharge roller pair, guide the conveyed second sheet into the second path, hold the first sheet in the first path, convey the second sheet by a specified extent and then hit against the discharge roller pair, and discharge the first sheet and second sheet in superimposed state on the stacking tray by the discharge roller pair.
According to the invention, by aparting the discharge roller pair from each other, the sheet can be stacked in a state of sheet front end projecting from the discharge roller pair, and therefore not only the space for temporarily placing the sheet can be used as the conveyance path before discharge roller pair, but also the space above the stacking tray can be used as temporary stacking space. As a result, unlike the prior art, it is not required to have a wide space for placing the sheets temporarily in the conveyance path before the discharge roller pair, and therefore decline of throughput can be prevented without increasing the size of the apparatus. Besides, abutting of front end is not required at the time of temporary placing, sheet damage by abutting of front end can be prevented. Besides, jamming by sheet buckling due to abutting of front end is avoided, and a product of high reliability can be provided. When superimposing the second sheet, the second sheet is not stopped temporarily, and jamming of paper space between the second sheet and a third sheet is avoided, so that a sufficient aligning process time can be reserved.
[First Embodiment]
First, referring to
The image forming apparatus 100 includes a controlling device 110 for controlling various operations, and the operation of sheet processing apparatus 200 described below is also controlled by the controlling device 110. A control unit may be provided at the sheet processing apparatus 200 side, and the operation of the sheet processing apparatus 200 may be controlled through this control unit.
The sheet S of which image side is fixed in the upper side state is conveyed in a U-shaped sheet conveyance route up to discharge roller 105 as shown in
Referring to
As shown in
The stacking tray 203 includes a return roller 204 for aligning the stacked sheets in the sheet conveying direction, a reference wall 205 against which rear ends of sheets returned by the return roller 204 abut, a lateral aligning plate 206 for aligning the sheets in a direction orthogonal to the sheet conveying direction, a stapler H for sewing the matched sheet bundle, and a discharge roller 207 for discharging the post-processed sheet bundle to the discharge tray 208 outside of the machine.
In this constitution, the conveyance route is changed over to the sheet processing apparatus 200 side by the discharge port switching flapper 106, and the sheet S is introduced into the sheet processing apparatus 200 by the transfer roller 108. The sheet S is discharged onto the stacking tray 203 by the discharge roller pair 202, and matched and processed by the return roller 204 and lateral aligning plate 206, and sewn and processed by the stapler H, and discharged outside of the machine as sheet bundle by the discharge roller 207.
Referring now to
In this period, the sheet S21 is conveyed through the first path 209 without stop, and the sheet front end passes over the discharge roller pair 202 (
Next, when the front end of sheet S21 has passed over the discharge roller pair 202, the discharge roller pair 202 is aparted. Further, when the sheet rear end of sheet S21 has passed over the first path roller 201, the switching flapper 212 is changed over, and the front end of sheet S21 projects into the upper space of the stacking tray 203, and the sheet rear end is held by the switching flapper 212 in the first path 209. At the same time, sheet S22 of second job can be introduced into the second path 210 (
In succession, while the first sheet S21 is being held by the switching flapper 212, a second sheet S22 is conveyed into the second path 210. At this time, the discharge roller 207 nips and conveys the sheet bundle S1 of preceding job, and the sheet bundle S1 is discharged (
The sheet S22 continues to be conveyed by a specified distance by the second path roller 211, after the sheet rear end has passed over the first path roller 201, until it is aligned with the front end of sheet S21 or the front end of sheet S22 moves ahead of the front end of sheet S21. At the timing of the front end of sheet S22 aligning with the front end of sheet S21, or the front end of sheet S22 moving ahead of the front end of sheet S21, the discharge roller pair 202 is compressed (
The sheet S22 is superimposed on the sheet S21 and discharged onto the stacking tray 203, and the return roller 204 pushes the sheet rear end against the reference wall 205 and matches in the sheet conveying direction, and at this time, the return roller 204 acts only on the top of the sheet S22. The return roller 204 continues the returning action until the rear end of the upper sheet S22 abuts against the reference wall 205, but by the frictional action between sheet S22 and sheet S21, sheet S22 and sheet S21 are pushed back together. At this time, if the sheets are stacked with the front end of sheet S22 with projecting, first, the rear end of sheet S21 hits against the reference wall 205, and then the rear end of sheet S22 hits against the reference wall 205, and aligning is complete, but on the contrary if the sheets are stacked with the front end of the first sheet S21 with projecting, aligning is complete when the front end of sheet S22 hits against the reference wall 205. This is the reason why the front end of the second sheet S22 is moved ahead of the front end of the first sheet S21.
Incidentally, the second path 210 is disposed outside of the first path 209, that is, at the opposite side of stacking side on stacking tray 203 with respect to the conveying side of the first path 209, and hence the sheet S21 is located at the stacking tray 203 side from the sheet S22. Since the sheets are discharged face-down, with the image surface at the stacking tray 203 side, with sheet S22 superimposed on sheet S21, the sheets are stacked in the page sequence. Herein, the sheet S22 does not stop until discharged onto the stacking tray 203. The lateral aligning plate 206 completely moved away to the sheet receiving position (outside of sheet passing range) before sheets S21, S22 arc discharged onto the stacking tray 203.
Afterwards, until a third sheet S23 is fed in, the return roller 204 matches in the sheet conveying direction, and the lateral aligning plate 206 matches in the orthogonal direction to sheet conveying direction (
[Second Embodiment]
A second embodiment of sheet processing apparatus of the invention is described.
This embodiment is different from the first embodiment in the shape of the conveyance path from first path roller 201 to discharge roller pair 202.
As shown in
Referring to
In this embodiment, same as in the first embodiment, after the final sheet S1L of preceding job is discharged, it is matched and sewn, and in this process, a first sheet S21 of next job is conveyed (
In this configuration, if the sheet processing apparatus does not have a widely curved path as in the first embodiment, at least the front end of second sheet S22 does not push out the first sheet S21 by friction. Therefore, in addition to the same effects as in the first embodiment, since curve path is not particularly required, the apparatus can be composed by using paths of free shape, and the apparatus may be further reduced in size, and it is possible to connect to various image forming apparatuses, and the applicability of the apparatus can be extended.
[Third Embodiment]
A third embodiment of sheet processing apparatus of the invention is described.
This preferred embodiment is different from the first embodiment in the aligning means in a direction orthogonal to sheet conveying direction.
In a sheet processing apparatus 500 shown in
Referring to
In this period, the sheet S21 is conveyed through the first path 209 without stop, and the sheet front end passes over the discharge roller pair 202. At this time, the lateral aligning roller 501 compresses the final sheet S1L, and matches the sheet in a direction orthogonal to sheet conveying direction (
When the front end of sheet S21 passes over the discharge roller pair 202, the discharge roller pair 202 is aparted. Further, when the sheet rear end of sheet S21 passes over the first path roller 201, the sheet S21 is held by the first path 209, with its front end projecting into the upper space of the stacking tray 203. At this tine, the switching flapper 212 is changed over, and second sheet S22 of next job can be introduced into the second path 210 (
The subsequent operation of stapling mode is same as in the first embodiment, and explanation is not described.
In this configuration, aligning in direction orthogonal to sheet conveying direction is realized by using a lateral aligning roller provided at the upstream side from the discharge roller pair 202, and the stacking tray 203 can be reduced in size, and the apparatus can be further reduced in size.
The invention is applied in a sheet processing apparatus for collecting, aligning and post-processing the sheets discharged from an image forming apparatus.
This application claims priority from Japanese Patent Application No. 2004-249952 filed Aug. 30, 2004, which is hereby incorporated by reference herein.
Number | Date | Country | Kind |
---|---|---|---|
2004-249952(PAT.) | Aug 2004 | JP | national |
2005-235114(PAT.) | Aug 2005 | JP | national |